Multiple unmanned aerial vehicle (UAV) team often needs to perform some certain tasks cooperatively. In the process of UAVs performing these tasks, the bandwidth of the communication network will affect the task assignment results, then the problem of task allocation for multi-UAV teams under the condition of limited communication bandwidth is considered. For a target, UAVs need to perform reconnaissance, attack and assessment tasks in coordination. The Consensus-Based Bundle Algorithm(CBBA) requires each task is assigned to no more than one UAV, so this paper extends CBBA by duplicating cooperative tasks to modify the task list and adding a judgment mechanism to ensure the uniqueness of the duplicate tasks' allocation in order to achieve the purpose of allocating multiple UAVs to the same task. At the same time, this paper utilizes a bid warping link to improve the algorithm performance and applies CBBA in asynchronous environment to reduce communication burden. Simulation results show that this improved algorithm is feasible and more efficient to improve the task allocation result for multi-UAVs teams with fewer messages transmission and a larger global reward.